Phase diagrams of the Bose–Fermi–Hubbard model at finite temperature

Abstract

The phase transitions at finite temperatures in the systems described by the Bose-Fermi-Hubbard model are investigated in this work in the framework of the self-consistent random phase approximation. The case of the hard-core bosons is considered and the pseudospin formalism is used. The density-density correlator is calculated in the random phase approximation and the possibilities of transitions from superfluid to supersolid phases are investigated. It is shown that the transitions between uniform and charge-ordered phases can be of the second or the first order, depending on the system parameters.

Energy Spectrum of the Pseudospin-Electron Model in a Dynamical Mean-Field Approach

“…STASYUK, V.O. KRASNOV, 2013 used, one has to do with a pseudospin-fermion analogue of PEM [11]. The transverse field exists here in the phase with a Bose-Einstein (BE) condensate and is proportional to the order parameter S x , while the longitudinal field plays the role of a chemical potential of bosons.…”

Bose-Fermi-Hubbard model on a lattice with two nonequivalent sublattices

“…t 2 = 1/4, and t 1 = 1/6, t 2 = 1/4, but here we do not present these diagrams because they are similar to that shown in figure 3). With an increase of temperature, the first order phase transition transforms into the second one and then disappears at some critical value of the temperature, as it was discussed in our previous work [10] at the construction of T − h diagrams in the case t 1 = t 2 . The case E = 0 is illustrated in figure 4.…”

“…It should be noted that almost all the mentioned studies were restricted to the case of zero temperature. In our previous work [10] we analyzed phase transitions in the BFHM at finite temperature.…”

“…The experimental verification of this phase transition was done by Greiner et al [3] and the study of this model has rapidly developed since then. Besides the bosonic atoms, the mixture of bose-fermi atoms in optical lattices was realized and the Bose-Fermi-Hubbard model (BFHM) is under intensive investigations [4][5][6][7][8][9][10]. As concerns the BFHM, phase diagrams are more complicated because the effective interaction between bosons is generated due to the presence of fermions and this leads, for example, to the possible appearance of a supersolid (SS) phase (which is characterized by a simultaneous presence of a density wave and phase order in the condensate).…”

Phase transitions in Bose-Fermi-Hubbard model in the heavy fermion limit: Hard-core boson approach

“…For boson-fermion mixtures, the BFH model in hard-core bosons limit remains less explored. In [48], the phase diagrams and phase separation or charge modulation conditions at the ion intercalation in semiconductor crystals were investigated based on the BFH-type model; in [49,50], within pseudospin-…”